LED incandescent lamp retrofit lamps which include light-emitting diodes (LEDs) as light sources, and which are intended to replace conventional incandescent lamps, are known. To this end, the incandescent lamp retrofit lamps should not substantially exceed an external dimension of the conventional incandescent lamp. At the same time, an incandescent lamp retrofit lamp should also be able to replicate the essentially omnidirectional light distribution of the conventional incandescent lamp. This, however, is not readily possible owing to the directional light emission characteristic of light-emitting diodes. During operation, it is furthermore necessary to ensure sufficient cooling of the light-emitting diodes, to which end a heat sink is used. However, the heat sink obscures a part of the surrounding space, so that omnidirectional light emission is made more difficult. The light-emitting diodes are typically arched over by an optically transmissive bulb.
One possibility for at least approximating omnidirectional light emission consists in using an incandescent lamp retrofit lamp having a plurality of light-emitting diodes, which are oriented in different directions. The superimposed light distributions of the light-emitting diodes give the overall emission pattern of the incandescent lamp retrofit lamp. This, however, entails an either relatively large-area or relatively complicated (and therefore elaborate to install) arrangement of the light-emitting diodes.
Another possibility for approximating omnidirectional light emission consists in coating the bulb with a luminescent material (“remote phosphor”), the luminescent material partly wavelength-converting light incident thereon from an LED, and partly re-emitting it diffusely without wavelength conversion. However, such a lamp is elaborate and furthermore cost-intensive in its design.
Another possibility for approximating omnidirectional light emission consists in using reflectors. However, these cause shadowing and an efficiency loss.